Shape adaptable intramedullary fixation device

ABSTRACT

Implantable devices for fixation of curved bone such as the pelvic ring pubic symphysis and acetabulum, and methods for the use of the devices are disclosed. The implantable devices are convertible between a flexible state and a rigid state, and include an elongate structure having a proximal bone interface, a main body, and a distal bone interface. In a flexible state, the devices may be inserted along, and conform to a curved pathway, and in the rigid state, the devices may support the mechanical loads required to fixate a fracture.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation under 35 USC §§365(c) and 120 ofInternational Application No. PCT/US2015/018969, filed on Mar. 5, 2015,which claims priority to U.S. Provisional Application No. 61/949,177,filed Mar. 6, 2014, which are each incorporated herein by reference intheir entirety for any and all purposes.

BACKGROUND

Bone fractures may occur in straight bones, such as the femur, or incurved bones, such as pelvic bones. Repairing a bone fracture generallyinvolves two steps: fracture reduction and fracture fixation. Reductionis the step of reducing the fracture by minimizing the distance betweenthe bone fragments and aligning the bones anatomically to minimizedeformity after healing. Both surgical and nonsurgical reduction methodsexist. Fixation is the step of holding the bone fracture fragmentsmechanically stable and in close proximity to each other to promote bonehealing which may take several weeks or more, depending on the type offracture, type of bone and the general health of the patient sufferingthe injury.

Fixing bone fracture fragments in a mechanically stable manner toeliminate motion across the fracture site also minimizes pain whenpatients apply weight across the fracture during everyday activitieslike sitting or walking. Fixation of bone fractures may be accomplishedby either internal or external fixation. Internal fixation is defined bymechanically fixing the bone fracture fragments with implanted devices.Examples of internal fixation include bone screws inserted within thebone across the fracture site and bone plates which are applied to thesurface of the bone across the fracture site. Bone plates are typicallyattached to healthy bone using two or more bone screws.

External fixation is defined by methods and devices which mechanicallyfix the bone fracture fragments with devices or methods external to thebody. The traditional use of a splint or cast are examples of externalfixation of a fractured bone. An example of an invasive externalfixation device uses long screws that are inserted into bone on eachside of the fracture. In pelvic fracture work the use of externalskeletal fixation is common and involves placing long threaded pins intothe iliac bones and then connecting them with an external frame. Thesescrews are connected to a frame which is located outside the body.

Invasiveness of both fracture reduction and fixation steps variesdepending on the devices and/or methods used. Invasive open reductiontypically involves surgically dissecting to allow access the bonefracture. Dissection is performed through the skin, fat, and musclelayers, while avoiding injury to adjacent structures such as nerves,major blood vessels, and organs. Once dissection has been completed, thefracture may be reduced prior to definitive fixation and provisionallyheld using surgical clamps or other methods. Non-invasive closedreduction is typically performed by applying force to the patient's skinsurface at different locations and/or to apply traction to a leg, toreduce the fracture. Minimally invasive reduction techniques minimizethe surgical dissection area by reducing the size of the surgical woundand by directly pushing on the bone with various long handled toolsthrough the minimal surgical wound. Invasive open fixation typicallyinvolves surgically dissecting to allow access to sufficient areas ofhealthy bone so that fixation devices such as surgical plates can beattached directly to the bone surface to fix the fracture site.Minimally invasive closed fixation typically involves insertion of adevice such as a bone screw or intramedullary rod (or nail) within thebone through a small incision in the skin, fat, and muscle layers.

Minimally invasive reduction and fixation are typically used to repairlong bone injuries such as the femur. One example is an intramedullaryrod, also known as an intramedullary nail (IM nail), inter-locking nailor Küntschner nail. Intramedullary nails in the femur and tibia are loadsharing devices and can well resist large bending and shearing forces,thereby allowing patients to leave hospital and manage with crutches ina short time.

The mechanical strength of bone fixation is determined by both thestrength of the implant and strength of the implant's attachment tohealthy bone. The mechanical forces applied across the fracture duringthe healing process can include shear, compression, tension (tensile),torsion, static loading and dynamic loading. In bones with complexcurvature such as bones of the pelvis (FIG. 1) or of the spine, straightintramedullary fixation devices have limitations. Bone curvature limitsthe mechanical strength of attaching a straight intramedullary fixationdevice within healthy bone tissue. In pelvic and acetabular fracturefixation, and example of a straight intramedullary device is a commonlyused cannulated bone screw. These screws must be limited in length anddiameter because they are a straight device in a curved tunnel. If toolong they will penetrate the bone and could injure important softtissues. However, such screws may not offer secure fixation due to theirlow tensile pull out forces in cortical cancellous and/or osteoporoticbone during the healing process. Also, the diameter of the straightintramedullary screw, when in a curved bone, is significantly smallerthan the thickness of the cancellous bone layer between the two outercortical bone layers. Since the cancellous bone is significantly weakerthan cortical bone (and can have significantly compromised strength inthe case of osteoporotic bone) straight intramedullary screws may allowfor the bone fragments to move relative to each other due to inadequatevertical shear holding force of cancellous bone. Plates normally act,mechanically, as tension band plates, neutralization plates orcompression plates. Often a single plate will perform more than one ofthese mechanical functions, but since the plates are attached to thebone, the use of plates requires invasive open surgery to expose thebone. The plates are inherently weak because they have to be designed tobe thin and have notches in them so that they can be bent to fit thecurves of the pelvis. Invasive open surgery can result in increasedblood loss, increased risk of infection and increased healing timecompared to minimally invasive methods.

SUMMARY

Difficult mechanical fixation issues associated with fixation of curvedbones such as are found in the pelvic ring and around the acetabulum,may be minimized or eliminated by using implantable devices that may beconvertible between a flexible and a rigid state. These devices mayinclude an elongate structure, a proximal bone interface, a main body,and a distal bone interface. In a flexible state, the device may beinserted inside, and conform to a curved pathway, and in the rigidstate, the device may support the tensile and vertical shear mechanicalloads required to fix fractured bone segments. The insertion process mayinvolve screwing the device into bone. Other embodiments aresufficiently flexible to be inserted inside a curved path andsufficiently rigid after implantation without requiring aflexible-to-rigid conversion step. A fixation system may include thecurved intramedullary fixation device, a guide wire, a reamer, and anextraction tool. Methods of use may include usages of a curvedintramedullary fixation device for fixation of pelvic ring andacetabular fractures, intramedullary guide wire placement within curvedbone, curved intramedullary fixation device implantation over a guidewire, intramedullary fixation device attachment to bone at implantdistal end, intramedullary fixation device attachment to bone atproximal end, and in some embodiments device conversion between flexibleand rigid states. In an embodiment, there is a medical apparatus forbone fixation. The apparatus has a flexible body defining a main axis.The flexible body has a proximal end and a distal end. The flexible bodyis made up of several individual segments having a mechanical engagementstructure for non-rigidly interlocking the individual segments together.The segments have a plurality of channels or apertures arranged togenerally form two or more lumens in the flexible body when the segmentsare in non-rigid mechanical engagement. The individual segments may moverelative to each other in a first and a second orthogonal plane relativeto the main axis. The medical apparatus has a torque transmission memberpositioned substantially on the proximal end. There is a bone engagementfeature positioned substantially on the distal end. There are one ormore fibers extending through the lumens such that the fibers provide afixed shape to the flexible body when the fibers are fixed intoposition.

In an embodiment, there is a medical device for bone fixation, thedevice has an elongate tubular body defining a first axis, the bodyhaving a proximal end, a distal end and a lumen there through. Thetubular body has a series of slots, cuts or apertures in it. There is atorque transmission member located generally at the proximal end. Thereis a bone engagement feature located generally at the distal end. Theseries of slots, cuts or apertures provide stress relief along theelongate body when the tubular body is under torque.

In an embodiment, there is a medical device for fixation of fracturedbone, the device has an elongated body defining a longitudinal axis, andhaving a proximal end and a distal end spaced longitudinally from theproximal end by a first distance. There is a flexible body portionextending along at least a portion of the first distance, the flexiblebody portion has a plurality of interconnected segments. Each segment ofthe interconnected segments defines an axis portion of the longitudinalaxis, and each segment is movable with respect to at least one adjacentsegment to angularly offset the axis portion of each segment with theaxis portion of the at least one adjacent segment. There is atransmission member positioned adjacent the proximal end for axiallyinserting the elongated body into the bone. There is a bone engagementdevice positioned adjacent the distal end for axially retaining theelongated body within the bone. There are two or more fibers disposedlongitudinally within the elongated body through at least the flexiblebody portion in circumferentially spaced relation to one another. Thereis a fiber tensioning system for tensioning individual fibers of the twoor more fibers to retain the interconnected segments in a fixedrelationship with each other, and the fibers with one another.

In another embodiment, there is a method of fixing a reduced bonefracture in a curved bone. The method involving creating an entry into acurved bone, advancing a guidewire through an intramedullary space to aposition distal to a reduced bone fracture, reaming a channel in theintramedullary space along the length of the guidewire, advancing acurved intramedullary fixation device through the channel and lockingthe curved intramedullary fixation device in place.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A-1B depict the human pelvis.

FIG. 2 depicts an embodiment of a curved intramedullary fixation deviceaccording to an embodiment.

FIG. 3A show a bone with a fracture.

FIG. 3B illustrates the device inside a broken bone.

FIGS. 4A-4D provide various embodiments of a core for the device.

FIGS. 5A-5E provide various illustrations of device segments.

FIG. 6 illustrates a stack of device segments in two views.

FIGS. 7A-7C provide an alternative embodiment of a segment.

FIG. 7D provides an illustration of segments being threaded together.

FIGS. 8A-8D provide an illustration of an alternative segment andsegment arrangement.

FIGS. 9A-9C provide alternative embodiments of segments.

FIGS. 10A-10C provide alternative embodiments of segments.

FIGS. 11A-11C provide alternative embodiments of segments.

FIG. 12 illustrates a segment stack using different kinds of segments.

FIG. 13A-13B provide an embodiment of a segment.

FIG. 14A-14D provide an alternative embodiment of a segment.

FIG. 15A-15B provide a stack illustration of a segment embodiment.

FIG. 16 provides a view of a device using a stack segment body.

FIG. 17 provides an alternative embodiment of a device using a stacksegment body.

FIGS. 18A-18B provide an alternative embodiment of a segment with afulcrum engagement.

FIGS. 19A-19B provide two views of a distal section embodiment.

FIG. 20A shows a profile view of a distal segment.

FIG. 20B shows a cut away view of a distal segment.

FIGS. 21 and 22 provide an illustration of proximal end cap.

FIGS. 23A-23F provide various alternative embodiments of proximal endsections.

FIGS. 24A-24D illustrate a toothed interior embodiment.

FIGS. 25 and 26 illustrate a unibody type device.

FIGS. 27 and 28 illustrate a unibody design with stress relief features.

FIGS. 29A-29B illustrate a unibody design with a cut line.

FIG. 30 illustrates various embodiments of a proximal end.

FIG. 31 provides an alternative embodiment of a distal end.

FIGS. 32A-32L illustrate a method of fixing a reduced bone fragment.

FIG. 33 illustrates a curved guidewire.

DETAILED DESCRIPTION

Described herein are various embodiments for the fixation of fracturedor broken bones. The systems, apparatus and methods described herein maybe used on long and straight bones, but are designed specifically totreat curved bones. Curved bones may be generally straight with asection having a curve or arc length, generally curved without adistinguishable straight segment, or a combination of the two. Curvedbones or non-linear bones include the zygoma, mandible (jaw bone),clavicle, scapula (the hemipelvis of the upper limb), ribs, spine, talusand calcaneus. The device may also have some applications in pediatriclong bones.

Treatment of an injury or weakness in these curved bones may involve theuse of a bone reinforcement structure for deployment within the bonessoft interior (marrow or bone channel). The use of straightintramedullary nails and bone screws and plates are well known and oftenused for straight bones. Curved intramedullary nails are used in thehumerus and clavicle bones to reduce the invasiveness of theimplantation procedure. However, curved intramedullary nails are notused in the pelvis because the curvature of the pelvis variessignificantly depending on the size of the patient and the location ofthe fracture(s). Therefore, the deployment of a curved nail into curvedpelvis bones would be fraught with inherent difficulties, such asmatching the curvature of the nail to the bone, penetrating the nailthrough the desired path in the bone without piecing the cortical boneand thus further weakening the bone structure, visualizing thedeployment path, visualizing the placement in real time and removing thenail from the patient in the event the nail needs to be withdraw postprocedure for any variety of reasons. Another problem with trying to puta preformed curved nail into the pelvic ring or anterior or posteriorcolumns of the acetabulum is the paths formed are complex S shaped. Toget the preformed device past the first part of the complex S into thesecond part is impossible. The complex S shaped curves are threedimensional S's and have more than one S curve in them.

In the discussion of the various systems, devices and methods herein,references and orientation are made to facilitate the understanding ofthe described embodiment. The term “proximal” as used herein means theside or end of a device that tends to be the closest to the physician oroperator when using the described embodiment. Alternatively “proximal”means the side or end of an embodiment that is the last to enter apatient body. The term “distal” refers to the end or side of theembodiment that is furthest away from the physician or operator. Theterm distal may alternatively mean the end or side of the embodimentthat is first to enter the patient body. Several embodiments also makereference to a general axis. This axis is an imaginary axis based on theshape of some of the embodiments of the device and refers to the longaxis of the embodiments having one dimension (of height, length orwidth) clearly longer or greater than the other two dimensions. Thedimension which is the greatest is the dimension on which the generalaxis runs parallel to. Note the general axis may not be a straight line,and may be curved or follow a tortuous path, so long as the axis isgenerally thought of as running parallel to the embodiment. Parallel mayalso include superimposed in the same line, whether straight or curved.

Described herein is a curved intramedullary fixation device withadaptable or alterable shape capable of deployment within a bone orboney structure while having a flexible or non-rigid form, then adaptingto an inflexible or rigid form after deployment. The curvedintramedullary fixation device with adaptable or alterable shape mayrevert to a flexible or non-rigid form subsequent to deployment foreither further adjustment or removal from the bone or boney structure.Other embodiments are sufficiently flexible to be inserted along acurved path and sufficiently rigid after implantation without requiringa conversion step. Herein after, any discussion of bone placement shallalso refer to boney structures, bone like structures or other supportorgans of an animal. The curved intramedullary fixation device withadaptable or alterable shape shall also simply be referred to herein asthe device, support device or the apparatus.

In various embodiments, the device has a proximal end, a shape lockinginterface or section, a distal end, and an intermediate section. Thedevice may be formed from a group of segments arranged in an end to endfashion, where each segment has a generally standardized shape. Invarious embodiments, the device may be flexible in two planes orthogonalto the general axis. In some embodiments, the device may be flexible inmore than two planes orthogonal to the general axis. In some embodimentsthe standardized shape of each segment may include a generallycylindrical body having a first end and a second end. The first end mayhave a protrusion extending from the cylindrical body, and thatprotrusion may be formed or shaped so as to engage an aperture orreceptacle shaped generally to receive the protrusion in a generallymale to female arrangement. The cylindrical body may have one male endand one female end at the first or second ends. Alternatively thecylindrical body may have two male ends or two female ends. When thecylindrical bodies are lined up to form the device, the arrangement canbe made so male ends are adjacent to and engage into female ends. Themechanical engagement need not be tight fitting. In various embodimentsit may be useful for the male and female ends to meet and have somedegree of slop in the fitting. By slop we mean that when the male andfemale ends are mechanically engaged, the adjacent segments are able tomove relative to each other without disengaging mechanically. In otherwords, the male and female connection maybe such that the adjacentsegments do not separate from each other when moved relative to theother in at least one plane.

In various embodiments, the support device may have a series ofcylindrical bodies arranged in an end to end fashion with a male tofemale mechanical arrangement. In some embodiments the generallycylindrical body segments may have holes or apertures running parallelto the general axis. The holes may form one or more lumens in thesupport device when the segments are generally lined up. In someembodiments, the cylindrical bodies form segments of the support deviceand may be shaped to provide atraumatic surfaces and edges to prevent orreduce incidental tissue damage within bone during a procedure to placethe support device within the bone, reduce injury when removing thesupport device, and also reduce the risk of aggravating the injury thesupport device is intended to help heal.

In some embodiments the segments of the support device may have a shortheight compared to the width of the segment, and in some embodiments thesegments may have long heights compared to the width of a segment. Instill other embodiments the segment height may be equal to the width. Insome embodiments the segments of the device may be substantially uniform(all being of the same basic design with no more than 15% variation inany angles, axial lines and dimensions between segments), or thesegments may be a completely mixed variety where no segment is similarto any other segment.

In some embodiments, the segments may have several holes in them thatare substantially parallel to the general axis of the device. The holesmay be arranged with a first hole in the center of the segment, with oneor more additional holes arranged around the center hole. The one ormore additional holes may be arranged in a regular arrangement aroundthe center hole, or the one or more additional holes may be arranged inan irregular pattern, such as having more holes on one side of thesegment than the other. The one or more additional hole may form one ormore lumens through the support device when the individual segments arelined up in the device.

In some embodiments the holes may be drilled through the segment afterthe segment is formed. Drilling may be achieved mechanically, or throughelectromagnetic machining techniques such as laser, electric dischargemachining (EDM), chemical processing or other techniques. In someembodiments the holes may be formed into the segment when the segment iscreated (e.g. during an injection molding process, die cast process orthe like).

In some embodiments the segments have additional components incorporatedinto their structures to facilitate with the movement or fixation of thedevice within the bone to be treated. In some embodiments, the segmentmay have a movable element within the segment, such as a co-axial innercore that may be moved relative to the segment outer ring. The innercore may be shaped such that as it rotates, it causes elastic or plasticdeformation of the outer ring, which may in turn help cause the outerring of the segment to expand in at least one dimension. Such expansionmay assist in helping the device anchor itself within the bone. Reversalof the rotation of the inner core may relieve the elastic stress andreturn the outer ring to its original shape, or cause a second plasticdeformation to cause the outer ring to change into a reduced profile,which may be useful for withdrawing the support device from the bone.

In some embodiments, the segments have one external form when the deviceis being deployed into the bone, and a second external form when thedevice transitions or converts to its rigid inflexible state. Themovable element of the segment may be one or more spur(s) or spike(s)which help anchor the support device in the bone. The spurs or spikesmay protrude from a segment upon activation. Activation may be throughmechanical means or via electromagnetic means.

In various embodiments, one or more fibers may be threaded through theholes in the segments, so that fibers extend from one end of the supportdevice to the other through the holes in the segments. In variousembodiments the holes are lined up to form lumens through the supportdevice, so as to not crimp, impede or otherwise damage the fibers. Invarious embodiments the fibers may be affixed to the most distal segmentand protrude from the most proximal segment. In some embodiments thefibers may be releasably engaged to the distal segment, and may bereleased from the segments and withdrawn from the segments when desired.In some embodiments the fibers that protrude from the most proximalsegment may be adjusted by tensioning the fibers, torquing the fibers,pulling the fibers, pushing the fibers or exerting no force at all onthe fibers. In various embodiments any combination of the above may beused on any number of the fibers at any time, and different forces(including no force) may be applied at any particular moment in time. Invarious embodiments, the force(s) applied to the fibers can be used todraw the segments closer together, push them apart, torque them indifferent directions, or hold the segments in a desired shape. Invarious embodiments the device shape is defined by a guidewire. Invarious embodiments, the fibers may be manipulated to fix the segmentsinto a rigid or inflexible curved shape. In some embodiments, the fibersmay subsequently be altered to return the support device into a flexibleor non-rigid shape. In various embodiments, the support device may beadvanced distally or retracted proximally while the support device iseither flexible or rigid. In some embodiments, the fibers may be cables,wires, rods or similar structures. The fibers may be made ofbiocompatible metal (for example, stainless steel, titanium or nitinol),alloys, polymers, biosorbable materials, ceramics, glass, carbon fiberor any combination of these materials. Additional materials are providedand/or described herein.

In some embodiments, the shape of the device is provided by theguidewire or guide pin used to make the initial entry into theintramedullary space of the bone to be treated. The guidewire used maybe one having a particular geometry to facilitate creating the desiredshaped path in a curved intramedullary space. The device may be insertedover the guide wire or guide pin and traverse the length of the guidewire. While the device traverses the length of the guide wire, itfollows the curvature of the guide wire and maintains that curvatureduring and after deployment. The fibers may be used to draw theindividual segments together and may or may not contribute to the shapesetting of the device when it is made rigid. Reference is madethroughout the present disclosure of a guide wire being used to make theinitial entry into the intramedullary space, and the device trackingover the guide wire. The guide wire may be a flexible or stiff wire, aguide pin or other device having similarly useful characteristics tomake the initial entry into a bone, and able to bear the device trackingover it. It is not essential that the guide wire be so robust that thedevice cannot alter the shape of the guide wire if desired.

In some embodiments, the proximal section of the support device maycontain one or more segments. The segments of the proximal section mayhave any of the features described herein and attributed to any segment,or may posses any of the following additional features. In variousembodiments, the proximal section may serve as the proximal boneinterface to anchor the proximal end of the support device to theexterior bone surface. In some embodiments this may be an individual orsingular component. In some embodiments the anchoring may be done by aset of components that together form an exterior surface that contactsthe cortical bone at the proximal end of the device. In someembodiments, the proximal section may have an interior surface thatmates with the support device. The mating of the proximal section andthe bone may provide for transferring load from the bone to the device.The load path begins in the bone, passes into the proximal end of thedevice, through the device, and along to the distal end, and back intothe bone (this assumes a fracture with heavily fragmented bone thatcannot be compressed at the fracture site). Alternatively, if the bonecan be compressed at the fracture, the load path is shared, passingthrough the bone in compression, and through the device in tension. Insome embodiments the proximal section may have a bone interface likeinternal threads. The internal threads may fit over some externalthreads of a shape locking device, or of the intermediate section, or ofthe rest of the support device.

In some embodiments the proximal end can transfer torque exerted on theproximal end to the body of the support device. In some embodiments thetorque transferred from the proximal end to the distal end can be usedto drive the support device through a bone channel, or other preparedpath through the bone. In some embodiments where the body of the deviceis made of multiple segments, torque transmitted to the proximal sectionmay also cause all subsequent segments and sections to rotate andexperience at least some of the torque imparted to the proximal end orsection. In some embodiments, the proximal end has a positive ornegative relief feature for receiving a torque transmission device. Thetorque transmission device may be any instrument capable of transferringor applying torque, from human fingers to a screw driver to an electricpowered drill.

In various embodiments, the proximal section may be shaped to facilitateengagement to the bone. In some embodiments the proximal end may have acone shape, where the base of the cone (the wide part) is at the mostproximal end, and the narrow part of the cone is connected to the mainbody of the support device. In some embodiments the proximal end may beshaped in an oblong manner so as to be partially tapered at both thedistal facing side and the proximal facing side of the proximal end.Such double tapering may ease the insertion of the proximal end to thebone, and facilitate the covering of the support device once implantedinto the bone.

In various embodiments, there is a shape locking section to convert theflexible configuration of the support device into a rigid or inflexibleconfiguration. In some embodiments, the shape locking interface may havean outer shell, an inner expanding member, fibers and a locking screw.The outer shell may serve as one jaw of a clamping mechanism for thefibers which may be threaded through the interface. The outer shell mayalso serve as a retaining member for the proximal section via anexternal thread. In some embodiments, the inner expanding member ispassed against the fibers feeding through the interface by theadvancement of the locking screw. In some embodiments the locking screwmay be tapered along its axis such that when advanced, it causes theinner expanding member to expand, and causing an interference fitbetween the outer shell, fibers and the inner expanding member. Theresulting interference fit between the various components causes thefibers to be locked into whatever tensioned position they were in whenthe force was applied. As previously noted, the fibers may be tensionedto various degrees to cause the segments of the support device to changeits curvature or shape.

In some embodiments, the support device may have more than one shapelocking member. Additional shape locking members may be positioned atvarious lengths along the support device and be locked downindependently. In some embodiments, locking down one shape lockingmember into one shape, and a second or third shape locking member downinto a different shape, allows the support device to become rigid in avariety of shapes (e.g. a “S” shape, with two oppositely shaped curves).

In some embodiments, the shape locking mechanism may be an outer tensionband and an inner support core. In other embodiments the lockinginterface may be one or more swage balls on each fiber where the fibersare held in place by an accessory tool. In some embodiments the lockingmechanism may use gear teeth on the fibers and on the inside of thesupport device. In still other embodiments the locking mechanism may usea locking cap for fixing the tension of the various fibers.

In some embodiments the distal section may have one or more boneinterface elements used to mechanically engage the bone. The distal endmay anchor the distal end of the support device into a fixed position inthe bone and prevent the distal end from moving. The distal end may be asingle component having multiple segments, it may be a single componenthaving a single segment, or it may be one or more components not thesame as one of the segments. In some embodiments the distal end has aradial diameter greater than the main body of the support device. Insome embodiments the distal end has a diameter the same as the main bodyof the support device, and in still other embodiments the distal end hasa diameter smaller than the main body of the support device.

In some embodiments, the bone engaging feature of the distal end may bea screw thread. In some embodiments the screw thread may have cuttingedges for cutting both when the distal end is rotated either clockwise(e.g. insertion), or counter clockwise (e.g. removal). In someembodiments the bone engaging feature may be a frangible screw. In someembodiments the bone engagement feature may be any one or more ofspikes, pins, clips, grommets, claws, bumps, wires, washers or similarfeatures that are able to provide mechanical engagement between thedistal end of the support device, and the bone.

In some embodiments the segmented support device may have a polymersleeve to help provide an atraumatic surface between the curvedintramedullary fixation device and the bone.

In various embodiments, the device may be a tubular body. The tubularbody may have a proximal end, a distal end, and a section in between theproximal and distal section. The tubular body may be flexible about twoaxes orthogonal to the general axis. In some embodiments, the tubularbody may be flexible about more than two axes orthogonal to the generalaxis. Flexibility about two orthogonal axes orthogonal to the generalaxis allows the device to follow a complex shape, for example a complexshape formed by a guide wire which was previously inserted into curvedbone(s). In some embodiments, the tubular body may have apertures, cutsor material removed from the main body. These apertures, cuts or removedmaterial may be arranged and shaped in such a manner as to promoteflexibility in the tubular body. The device could be one piece. Forexample a machined titanium or polyether ether ketone (PEEK) screw withreliefs in the body of the device to make the body flexible. In otherembodiments a proximal, body, and distal section could be mechanicallyattached to each other.

In some embodiments, a guidewire is placed under fluoroscopic guidanceand the curved intramedullary fixation device is inserted over theguidewire. Insertion of the device may be then be accomplished byscrewing the device into bone. In other embodiments, the device may beproperly positioned within the bone without using a guidewire.

In the various embodiments described herein, the curved intramedullaryfixation device may be composed from a polymer, a metal, an alloy, or acombination thereof, which may be biocompatible. For example, thefracture stabilization device can be formed from titanium or a titaniumalloy. Other suitable metals may include stainless steel,cobalt-chromium alloys, and tantalum. In some embodiments, metal alloyshaving shape memory capability, such as nickel titanium or springstainless steel alloys, may also be used. In some embodiments, thefracture stabilization device can be formed from a suitable polymerincluding non-degradable polymers, such as polyetheretherketone (PEEK)and polyethylene (PE), as well as modified versions of these materials(for example, PEEK+calcium phosphates and PE+vitamin E, metal coatings,or surface texturing). Additional non limiting polymers may include;polyether-block co-polyamide polymers, copolyester elastomers, thermosetpolymers, polyolefins (e.g., polypropylene or polyethylene, includinghigh density polyethylene (HDPEs), low-density polyethylene (LDPEs), andultrahigh molecular weight polyethylene (UHMWPE)),polytetrafluoroethylene, ethylene vinyl acetate, polyamides, polyimides,polyurethanes, polyvinyl chloride (PVC), fluoropolymers (e.g.,fluorinated ethylene propylene, perfluoroalkoxy (PEA) polymer,polyvinylidenefluoride, etc.), polyetheretherketones (PEEKs),PEEK-carbon fiber composites, Polyetherketoneketones (PEKKs),poly(methylmethacrylate) (PMMA), polysulfone (PSU), epoxy resins andsilicones. Additionally starch based polymers may be used.

Additional materials may include carbon and polyaramid structures, glassor fiberglass derivatives, ceramic materials, and artificialbiocompatible protein derivatives (recombinant derived collagen). Inother embodiments, the fracture stabilization device may be made of ametal and/or alloy segments with a polymer shell, or a sandwich styleand coaxial extrusion composition of any number of layers of any of thematerials listed herein. Various layers may be bonded to each other toprovide for single layer composition of metal(s), alloys, and/orpolymers. In another embodiment, a polymer core may be used with a metaland/or metal alloy shell, such as a wire or ribbon braid.

Additionally, at least a portion of the fracture stabilization devicemay include a bone integration surface to promote bone ingrowth,on-growth, and/or through-growth between the segments, if desired. Thebone integration surfaces can comprise a three-dimensional space toallow bone integration into and/or onto portions of the fracturestabilization device. The three dimensional space can be provided by athree-dimensional substrate, for example beads, and/or by the provisionof holes through the bone integration portions. Other methods forachieving bone integration can include the provision of an appropriatesurface topography, for example a roughened or textured area and/or bythe provision of osteoconductive coatings, such as calcium phosphates.The bone integration surface may enable the fracture stabilizationdevice to provide a metal and/or polymeric scaffold for tissueintegration to be achieved through the fracture stabilization device. Invarious embodiments, various materials may be used to facilitate,stimulate or activate bone growth. A non-limiting list of materials mayinclude hydroxyapatite (HA) coatings, synthetic bioabsorbable polymerssuch as poly (α-hydroxy esters), poly (L-lactic acid) (PLLA),poly(glycolic acid) (PGA) or their copolymers,poly(DL-lactic-co-glycolic acid) (PLGA), and poly(ε-caprolactone) (PLC),poly(L-lactide) (LPLA), (DLPLA), poly(e-caprolactone) (PCL),poly(dioxanone) (PDO), poly(glycolide-co-trimethylene carbonate)(PGA-TMC), poly(lactide-co-glycolide), polyorthoesters, poly(anhydrides), polyhydroxybutyrate, poly(l-lactide-co-glycolide)(PGA-LPLA), cyanoacrylates, poly(dl-lactide-co-glycolide) (PGA-DLPLA),poly(ethylene carbonate), poly(iminocarbonates),poly(l-lactide-co-dl-lactide) (LPLA-DLPLA), andpoly(glycolide-co-trimethylene carbonate-co-dioxanone) (PDO-PGA-TMC).

Furthermore, at least a portion of the fracture stabilization device maybe treated or coated with a calcium material, such as calcium deposits,calcium phosphate coatings, calcium sulfates, modified calcium saltssuch as Magnesium, Strontium and/or Silicon substituted calciumphosphates, RGD sequences, collagen, and combinations thereof in orderto enhance a strength of bone ingrowth, on-growth, and/or through-growthbetween the segments or other portions of the fracture stabilizationdevice.

The process of repairing or providing support to a bone to preventfurther degradation of the bone's structural integrity may involvediagnosis and understanding of the underlying cause for the bone injury,disease or weakness. Any diagnostic tool or procedure is not part of thepresent disclosure and does not form any aspect of the methods of usingthe system, apparatus and methods described herein.

Once the nature of the injury to be treated is understood and atreatment plan involving the herein described support device isconceived, the doctor or operator may proceed to access the bone wherethe support device is to be placed. In some embodiments the supportdevice is entered into the bone where there is a minimum of other bonejoints, nerve tissue and/or muscle mass so the use of the support devicehas the lowest probability of creating additional injury or increasingthe patient's recuperation time. Because there is a general desire topromote quick healing, the procedure involved in using the hereindescribed support device may be one that is minimally invasive. In someembodiments the procedure may be fully invasive. In some procedures thesupport device may have an increased length to allow the support deviceto enter bone far from the injury site, and still successfully navigatethe bone and injury site. In some embodiments, extra length of thesupport device may be relegated to the proximal end, where a greaterflexibility of segment choices are generally permitted. In someembodiments, the area of injury may be close to the access point to thebone, and to ensure proper fixation of the support device, the distalsegment may have increased length to engage in cortical bone or otherhealthy tissue sufficient to provide for bone fixation. Where the distalsection is elongated, regardless of the reason why the distal section iselongated, the choice of different segment types may also be generallyflexible.

In some embodiments, the support device as described herein may be usedin a procedure to promote fixation of a bone. In some embodiments, amethod of fixing a fractured or broken bone may utilize any one or moreof the steps such as creating a surgical incision in a patient to gainaccess to a bone surface, creating a hole in the bone, inserting a guidewire into the bone, navigating the guidewire along a curved path withinthe bone, feeding a flexible reamer over the guide wire, creating achannel for the support device, removing the reamer, advancing thesupport device into the bone, adjusting the shape of the support device,fixing the shape of the support device, and securing the support devicein the bone.

In some embodiments there may be one or more additional steps such asobserving the movement of the guide wire, reamer or device into thebone, threading one or more sections of the support device into thebone, securing the shape of the support device through one or morelocking mechanisms, rotating the support device, applying torque to thesupport device, applying torque to a section or segment of the supportdevice.

In some instances, it becomes necessary to remove a bone fixation devicefrom a patient. The support device of the present disclosure may beremoved following a series of steps similar to, but not necessarilyopposite of the implanting steps. In some embodiments, the supportdevice may be removed from the bone by: exposing the shape lockingfeature, returning the flexibility of the support feature, and removingthe support feature from the bone.

In various embodiments, removal of the support device may entail one ormore additional steps, such as exposing the proximal end formanipulation, disengaging the proximal end from the shape lockingfeature, removing the shape locking feature (or element), withdrawingthe support device, retracting any retractable bone engagement features,rotating the support device, applying proximally directed force on thesupport device or any of its sections and/or segments. Other embodimentsmay not use or require a shape locking element to be unlocked prior toremoval.

Discussion of the various embodiments, alternative arrangements andmethods of use are now further described in some forms by turning now tothe drawings. A notation used in the drawings may refer to various partswith a subscript, in particular part number X_(a-n), where X is thegeneral part number, and a-n refers to a sequence of parts, or numerousparts having many numbers. The use of a-n simply refers to the partsstarting with “a” and ending at some undetermined number “n.” The usehere is similar to the general use in mathematics when referring to anumber of variables from A to N. As a representative curved bonestructure, the pelvic ring 100 has several areas where short curved bonesections are present (FIG. 1). Some elements of the pelvis are the Ilium102, the Pectipeal Line 110, the Os Pubis 108, the Ischium 106 and thePubic Arch 104. The pelvic ring is a key structural element of theskeletal system because it is a weight-bearing structure interposedbetween the upper body and the legs. As such, if a fracture occurs andit is untreated, the pelvic ring may not heal (nonunion) or may heal ina poor position (malunion). Nonunion can lead to chronic pain and aninability to walk. Malunion can result in a short leg or one whichpoints in the wrong direction or an abnormal gait. There are variationsbetween the male and female pelvis and pelvic ring, and the malestructure is shown in FIG. 1. However the arbitrary selection of usingthe male pelvis is not to be taken as limiting or discriminating in anysense. The use of the technology described herein is designed andadaptable for use in both the male and female anatomy. Certainadjustments may be necessary to accommodate one or the other anatomy,and such adjustments will be evident to those skilled in the field ofbone fixation upon detailed study of the present disclosure.

A treatment of these kinds of fractures in curved bones may be utilize acurved intramedullary fixation device (device) capable of implantationinto a variety of curved pathways inside the bone. These curved pathwaysinside the bone may vary about two or more axes long the length of thedevice. Such a support device 200 may have a distal end 204, a main body206 and a proximal section 208. In some embodiments the supportstructure 200 in the many embodiments is the main body 206 can beflexible when delivered, and then made rigid or inflexible when thesupport device 200 is properly positioned. The transition between aflexible state and a rigid state may be achieved through various means,such as a shape locking mechanism. In other embodiments the main body206 is sufficiently flexible to be implanted along a curvedintramedullary path yet sufficiently strong enough to withstand tensileand vertical shear forces required to fixate the fracture(s). In otherwords, no transition step between flexible and rigid states is required.The distal end 204 and the proximal end 208 may have one or morefeatures to assist in engaging the bone.

A cross-sectional view of a fractured bone 300 with a support device 302is now described (FIGS. 3A-B). The depicted bone of FIG. 3A is straightfor ease of illustration only, all features of the support device 302are equally applicable to a curved bone. As represented in FIGS. 3A and3B, a bone 300 may include an outer cortical bone layer 312 thatsurrounds the cancellous bone 314. A fracture 316 may extend partiallyor completely through the bone 300, forming two separated bone portions300 a and 300 b. A fixation device 302 may generally include a main body322, with a proximal bone interface 324, and a distal bone interface326. The fixation device 302 may also include a shape locking interface,generally represented at 328.

Various embodiments of fixation devices 302, including variousembodiments of the main body 322, various embodiments of the proximalbone interface 324, various embodiments of the distal bone interface326, and various embodiments of the shape locking interface 328 arediscussed below. The four components are configured to be modular to adegree, such that the alternate embodiments described for each componentmay be interchangeable with one another, and may also be usable with anyof the embodiments of the other three components. All sections may bemanufactured using standard machining, electric discharge machining(EDM), metal injection MIM, traditional molding (MIM), polymer injectionmolding, metal casting, and/or forging methods, or any combination. Thevarious elements of the device may be produced from Titanium Grade 236Al-4V ELI material. Other implantable materials may also be feasiblefor use, including but not limited to 316 LVM Stainless steel, polyetherether ketone (PEEK), other any material considered biocompatible,materials, and or a combination of the materials previously described.

The use of the term “fiber” may refer to any variety of elongatedstrands of material, such as filaments or wire, having any of variouscross sections including, but not limited to, round, rectangular,square, and bundles (for example cable) of any of the former. The terms“fixing” or “to fix” refer to holding or setting something in place. Inparticular, a bone fracture may be fixed by causing a device placedacross the point of fracture to become rigid, thereby stabilizing thebone on either side of the fracture. Additionally, the device itself maytransition between a rigid state and a flexible state by actuating atransitioning member. The device may be highly flexible to navigate acomplex series of S curves, or semi-rigid and rather stiff to handle asimple curve. Regardless of the level of flexibility in the device, thevarious segments can be locked down to enhance the rigidness of thedevice.

The main body 322 may have at least one flexible portion that isconfigured to bend, rotate along, or follow a curved path. In anembodiment, at least a portion near the distal end 326 may be flexible,or alternatively, the entire body 322 may be flexible. For fixation ofbone, as represented in FIG. 3B, a fixation device 302 may be implantedto extend lengthwise across the fracture 316 to stabilize the bonesegments on each side of the fracture with respect to one another. Toaccess the bone 300, a small surgical incision may be made through theskin and soft tissue, and access to a bone surface may be provided by asystem of trocars and cannulae placed through the soft tissue. A holemay be made in the hard outer cortical bone layer 312 using a drill toaccess the interior (cancellous) bone 314. A, bent tip guide-wire may beplaced though the cannula into the interior of the bone, and the guidewire may be driven into the interior cavity of the bone underfluoroscopic observation. The sharp tip of the guide wire may beoriented toward the interior of the bone curvature, such that the tipdoes not dig into the exterior cortical wall. The guide wire willgenerally follow, and may be directionally guided through the interiorgeometry of the bone to a desired depth past the fracture 316. Ifdesired, the sharp tip guide wire may be exchanged for a blunt tippedguide wire. A flexible reamer, having a diameter appropriate for anintended support device 302 may be fed over the guide wire to create atunnel, or cannula, along the same path as the guide wire. The reamermay be withdrawn, leaving a curved tunnel or passage way for the supportdevice 302. Other embodiments do not require reaming prior to implantingthe device over the guide wire. These embodiments may includeself-drilling and/or self-tapping threads on the distal end of thedevice. For embodiments wherein the fixation devices include apertures,the guide wire may be left in place to guide the support device 302 intoplace.

In embodiments, the main body 322 may be configured as a one-piece body,or, alternatively, may be configured as a plurality of interconnectedsegments, or segments. The length of the support device 302 may varydepending on intended use, such as severity and location of thefracture, and stress that may be applied to the fractured bone. Inembodiments, the length may be about 80 mm, about 100 mm, about 120 mm,about 140 mm, about 160 mm, about 180 mm, about 200 mm, about 220 mm,about 240 mm, about 260 mm, about 280 mm, about 300 mm, about 400 mm,about 500 mm, about 600 mm, or any length between any of the listedlengths, or if needed, longer or shorter than the listed lengths. Thediameter of the support device 302 may also vary depending on intendeduse, such as severity and location of the fracture, and stress that maybe applied to the fractured bone. As a reference point, the diameter maybe defined by the outer diameter of features on the device distal end326. In embodiments, the diameter may be about 5 mm, about 6 mm, about 7mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about13 mm, about 14 mm, about 15 mm, or any diameter between any of thelisted diameters, or if needed, larger or smaller than the listeddiameters. The diameter of the device may be maximized for a particularprocedure to optimally full the intramedullary space between outercortical bone layers displacing weak cancellous bone and optimizing thestrength of the bone fixation relative to, for example, a straightintramedullary screw. The device may be scaled up or down for treatinglarger or smaller animals than human beings. The bend radius of thesupport device 302 may also vary depending on intended use, suchlocation, and the curvature of the fractured bone in the vicinity of thefracture. In embodiments, the bend radius may be about 40 mm, about 45mm, about 50 mm, about 55 mm, about 60 mm, about 65 mm, about 70 mm,about 75 mm, about 80 mm, about 85 mm, about 90 mm, about 95 mm, about100 mm, or any radius between any of the listed values, or if needed,larger or smaller than the listed lengths. As a non-limiting example, asupport device 302 may have a length of about 150 mm, a diameter ofabout 10 mm, and a bend radius of about 60 mm.

In another embodiment, a filler 400 may have a length that fits withinthe interior of a cannula of a fixing device (FIG. 4AB, FIG. 29AB). Thefiller 400 may be cannulated and include a longitudinal cannula 402 tofit over a guide wire. An exterior of the filler 400 may include anumber of grooves 404 separated by dividers 406. The grooves 404 mayhave a cross-sectional configuration that matches the cross-sectionalconfiguration of the fibers. The grooves 404 have a semi-cylindricalbase for receipt of cylindrical fibers 408 therein.

In an embodiment, fibers 408 may be inserted into a fixation device to alength as needed, and the filler 400 may be guided to the entry. Thefibers 408 may be aligned with corresponding slots 404 on the filler400, and the filler may be inserted into the body of the device. Uponinsertion of the filler 400 into the device, the fibers 408 will aligninto the slots 404 and engage the teeth on the interior surface. In anembodiment, the filler 400 may also include an end plug 410 that limitsmovement axially into the fixation device, and provides a gripping areafor gripping the filler during installation, and allows for gripping thefiller for removal, if removal is or becomes necessary. Upon removal ofthe filler 400, any engaged fibers 404 may then disengage from theinterior and also then be removable as well.

In an embodiment of a fixation device, the body may have a smoothinternal surface instead of threads, and a flexible filler 400 andfibers 408 may be longitudinally disposed within the body, with thefiller configured to separate and support the fibers within thelongitudinal grooves 404. The body may be shape-locked by tensioning thefibers 408 within the body. A first end of fibers 404 may be attached tothe distal bone interface or the end 82 a of the filler 400. The secondend of the fibers 408 may extend through the plug 488 and beyond the end482 as represented in FIG. 4D. In its flexible state, the fibers 408 andfiller 400 may be movable axially with respect to one another to therebyallow the support device to bend during insertion along a curved path.Once the support device is in place within the bone the fibers 408 maybe tensioned and fixed in place (in a manner as discussed further below)with respect to the end 82 b thereby minimizing, or prohibiting furtherrelative axial movement between the fibers and the filler 408, andeffectively shape-locking the configuration within the bone.

In additional embodiments of the support device, the body may include aplurality of individual interconnecting segments, or segments. In anembodiment as represented in FIGS. 5A-5E, at least a portion of afixation device 500 may include a body portion 502 that is formed from aplurality of segments 504. In an embodiment, the segments 504 may becylindrical discs, columns or other generally stackable elements,collectively referred to as segments. In alternative embodiments, thesegments may have other cross-sectional configurations, such astriangular, rectangular, hexagonal, octagonal, or various other shapes.Each segment 504 may include a hollow core 508, allowing for passage ofa guide wire 510, which may be used to direct the device into/through abored hole as discussed above. The segments 504 may have various heights504 h and diameters 504 d, wherein the diameters may be selected fromthe diameters as previously described. Further embodiments of segmentsof various ratios of height to diameter are presented further below.

Each segment 504, may include a first face 520 and a second face 518,disposed opposite the first face, and the segments may stack in aseries, as shown in cross-section in FIG. 5B, with first faces of onesegment adjoining second faces of an adjacent segment. At least one ofthe first face 520 and the second face 518 may include a centering pivot522, that engages within a corresponding recess 516 of the other of thefirst face and the second face of a sequential segment in the series. Inan embodiment as shown, one face may include the pivot 522 and the otherface the recess 516. In alternative embodiments (not shown), foralternating segments, each face of one segment may include the pivot522, and each face of an adjoining segment may include the recess 516.

To limit segment to segment angulation, or pivot of one segment onanother segment, to a pre-determined maximum value, at least one of thefirst or second face surfaces 520 and 518 may be disposed with anangular inclination 518 a, while the other surface may be essentiallyflat. In an embodiment, as shown in FIG. 5C, surface 520 may be highertowards the pivot 522 than at the periphery, and the surface 518 may beessentially flat. In an alternative embodiment (not shown), the surfacewith the recess 516 (surface 518 in FIG. 5C) may be the angled surface,and the surfaces having the pivot 522 may be flat.

The angular inclination 504 a may therefore provide one limit fordefining a minimum bend radius of the body 502. For example, stackedsegments 504 with larger inclination angles 504 a may bend to a tighterradius of curvature than segments having a smaller angle 504 a. Inembodiments, for example, the angle 504 a may be about 2°, about 3°,about 4°, about 5°, about 6°, about 7°, about 8°. about 9°, about 10°,about 11°, about 12°, about 13°, about 14°, about 15°, 18° or any anglebetween the listed values or greater than the listed values.

A height 504 h of the segments may also provide a limit for defining aminimum bend radius of the body 502. For example, stacked segments 504with smaller heights 504 h may bend to a tighter radius of curvaturethan segments having larger heights 504 h. In embodiments, for example,the height 504 h may be about 3 mm, about 4 mm, about 5 mm, about 6 mm,about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12mm, about 13 mm, about 14 mm, about 15 mm about 15 mm or any valuebetween any of the listed values.

In an embodiment as depicted in FIGS. 5A and 5B, the segments 504 may bestacked and then inserted within a flexible sheath 514. In embodiments,the sheath may have a wall thickness of about; 0.5 mm, about 1 mm, about1.5 mm, about 2 mm, about 2.5 mm, about 3 mm, about 3.5 mm, about 4 mm,about 4.5 mm, about 5 mm, or any value between any of the listed values.Depending on the tension-locking method used, the interior of the sheathmay be smooth, threaded or toothed and may have a smooth internalsurface. In some embodiments the sheath may have similar features to anouter layer of a catheter, being generally smooth and low friction withgreat bendability. The outer sheath may be made entirely of a lightweight polymer, and may be a mono-layer or multi-layer sheath. Thesheath may be reinforced (such as with a wire or wire ribbon braid) topromote pushability, or rely on the support device for both axial andradial support to prevent collapse. In some embodiments the sheath maycollapse and “shrink fit” on the support device, while in otherembodiments the sheath may have a gap space between the body of thesupport device and the sheath. Such gap space may be used for theinjection of fluids, medicines or antibacterial compounds.

To shape-lock the segments 504 in a desired configuration afterinsertion of the device 500 into a fracture location, the segments mayinclude a plurality of bores 524 disposed substantially parallel to thecentral core 508 and spaced circumferentially about the central core.Bores 524 may be configured to separate and support a series of tensilefibers 512 (one of which is represented in FIG. 5B) that may extendlongitudinally through the aligned bores of sequentially stackedsegments. In the flexible state, the fibers 512 may be axially fixed tothe distal bone interface 506 only, with the fibers free to translatethrough their respective bore holes in each segment. When a tension isapplied to the fibers 512 and the tension is locked with respect to thesegments 504, via the proximal bone interface in a manner as discussedfurther below, translation of the fibers becomes limited and thesegments become shape-locked with one another to maintain an overallshape of the device 500.

In an embodiment, three or more fibers 512 may be included to providesegment fixation about all planes of movement. Each bore hole or channel524 may not require a fiber 512, depending on the required strength andstability needed for the fixation device. Additional tensile fibers 512may be added to provide additional strength, as well as a more uniformflexural stiffness in any bending axis with respect to the fiberspattern orientation. For segments 504 having six bore holes 524, three,four, five or six fibers may be provided within the segments, with atleast one fiber in each of the positions disposed at about 120° from oneanother about the central bore 508 (see FIG. 6D).

As discussed further below with regard to tensioning of the fibers 512,the fibers may terminate within the main body, or in members attached toeither end of the main body, for example, the distal bone interface 506.The bore holes 524 in each segment 504 may form a lateral support foreach fiber 512, keeping the fibers away from the neutral bending axis.When the assembly is made rigid, the assembly may experience atransverse load, the transverse load creates a purely tensile load inany fiber on the opposite side of the bending axis from the transverseload, a compressive load between bead segments, and a reduction intension in the fibers on the adjacent side of the neutral axis

Alternatively, with all fibers in the construct fixed in length, andeach radially constrained but not under initial tension, loads appliedto induce bending could result in a set of compressive fibers on oneside of the neutral bending axis, and a set of tensile fibers on theopposing side of the neutral axis. In this construct, the load pathsupporting bending does not transmit a compressive load across segments.

In addition, the assembly of the fibers 512 inside the holes 524 of eachsegment 504 provides a torque transmission capability equal to the shearstrength of the sum of at least two fibers, and at most the total numberof fibers in the assembly. The torque transmission capability locks thetorque between adjoining segments and thereby provides for a screw-ininsertion of the fixation device, as the torque may be transmitted fromthe proximal end, through the segments 504 to the distal bone interface506 via the fibers 512.

In the embodiment as depicted in FIGS. 5D and 5E, a segment 504 mayinclude six bores holes 524 disposed at a spacing of about 60° so thatthe bore holes maintain tensile fibers 512 at a distance from the centerof the segment, as well as in a specific radial positions of about 0°,60°, 120°, 180°, 240°, 300°, and 360° relative to one another about thecentral core 508. Additional segment embodiments are discussed below.

In some embodiments, one or two bore holes 524 may be used to change theshape of the body 500. In some embodiments the body 500 may have apredisposed bend to it and a single fiber 512 may be used to offset thepredisposed bend to relax or reduce the curvature of the body 500 duringdeployment and shape fixing. Alternatively two fibers 512 may be used atvarious radial positions about the center to perform a similar function.In still other embodiments, one or more fibers may be disposed outsidethe body and under the sheath, and the fiber may be tensioned and fixedinto position to cause the desired shape setting (not shown).

In some embodiments, the individual segments 602 a-n may be stacked oneon top of another. The segments may have an angled surface on top orbottom allowing adjacent segments to lean off the main axis (FIG. 6A-B).The angled surface of each segment allows each segment to have a smallangle of deflection off the main axis from the adjacent segment (eitherabove or below). The deflection can be determined based on the angle ofthe surface 602 a. The sum of the angle deflections 610Σα off the mainaxis determines the curvature of the device 600. The deflection 602 a ofadjacent segments may be the same or it may be a higher or lowerdeflection. The stack of segments provides the section of the devicewhere the greatest number of deflections off axis can occur. The sum ofthe deflections 610Σα from the normal axis 610 is represented by thecurved axis 608. Here the segment stack is shown both in a plan view(FIG. 6A) and in a cross section view (FIG. 6B). In this view, thesegment height is less than the segment diameter, however this is merelyillustrative of one embodiment and in no way limiting. The segment mayhave a height equal or greater than the segment diameter.

In some embodiments, the individual segments 700 may have two or morebore holes or channels 702, 704 (FIG. 7A). A central bore hole orchannel 704 may be used for sliding over a guide wire or guide pin. Theperipheral channels 702 may be used for sliding over a fiber. Bystacking the segments 700 on top of each other (FIG. 7D), the segmentscan be aligned using a form a generally contiguous body. The segmentscan align on the central collar or positive relief feature 710. Thepositive relief feature 710 may be raised above the angled plane 712 dof the top surface 712 of segment 700. The difference in height betweenthe edge of the segment 700 and the positive relief feature 710 forms anangle 712 d. When the segments are stacked 700 a-n over the fibers 708a-n, they form the body of the multi-segmented device. The segments canbend relative to each other. By way of analogy only, one might envisionthe body of a centipede or millipede. The arthropod body is not flexiblebetween segments, but collectively with a higher number of segments, thearthropod body is able to curve on itself.

In some embodiments, the individual segments 800 may be tall, having aheight dimension 800 h which is greater than the diameter 800 d (FIGS.8A-D). The segment 800 may have a central bore hole or channel 802 and araised neck or positive relief feature 804. Any number of peripheralchannels 806 may be formed in the segment 800. These taller segments mayhave a standard form with a top surface having a positive relief feature804 and a bottom surface having a negative relief feature 810 (FIG. 8C).Stacking these segments provides a deflection angle 804 a between eachsegment. When the taller segments are used in place of the shortersegments in an implant of a certain height, it should be appreciatedthat the fewer number of segments with the same deflection angle willsum to a lower overall deflection angle. The sum of the deflection anglecan be increased or decreased by any combination of changing theindividual deflection angle on any one or more segments, or increasingor reducing the number of segments used in the same linear length of thedevice. Although two tall segments are shown in FIG. 8D, the segmentstack may include any combination of tall and short segments in a singleimplantable embodiment.

In some embodiments, the segments 900 (FIGS. 9A-9C) include six boreholes 904 disposed around the central bore 902 and configured for amaximum of six tensioning fibers. As discussed earlier, each bore holeor channel 904 may not need to have a tensioning fiber there through,and thus a fixation device having segments 900 may include three, four,five or six tensioning fibers, occupying at least three positions spacedat 120° around the periphery. Segments 1000 of FIGS. 10A-10C includeeight bores 1004 disposed around the central bore holes 1002 andconfigured for a maximum of eight tensioning fibers. As discussedearlier, each bore hole or channel 1002 may not need to have atensioning fiber there through, and thus a fixation device havingsegments 1000 may include four, five, six, seven or eight tensioningfibers, occupying at least four positions spaced at 90° around theperiphery.

A few additional embodiments of segments 1100, 1102, 1104 are depictedin FIGS. 11A-11C. As shown in the various embodiments, the segments mayhave various diameters, lengths, pivot configurations, number and sizeof bores, and surface inclination angles. In an embodiment, asrepresented in FIG. 12, the body of a fixation device may be formed fromsegments of varying configuration stacked together. For example aproximal segment 1202, adjacent the proximal bone interface, may belonger if the initial portion of a bore in the proximal section of thebone to be treated is relatively straight. In embodiments, end segmentsmay longer that those segments that are fixed about the curve, butdistal segments should be navigable about the curve the support deviceis designed to treat thus limiting to some degree the length of the mostdistal segments. A next section of segments 1204 may have anintermediate height, for example about 160 mm, if the bore hole in theintermediate section is relatively straight with minimal bending. Adistal set of segments 1206 may have a smaller height, for example about80 mm, to accommodate bending about smaller radii. In an additionalembodiment (not shown), proximal segments, such as segments 1202, 1204may also have a diameter that is greater than distal segments, such assegments 1206, possibly requiring that bore hole in the bone be drilledwith sections of different diameters.

In some embodiment, the segment may include one or more fulcrum elementsto facilitate r increase the off angle deflection between segments (FIG.13A-D). The segment 1300 has a base 1302 and a top surface 1310. The topsurface has a fulcrum element 1304. In some embodiments, the fulcrumelement 1304 may be rounded and symmetrical about the central channel1312, The fulcrum element may hace a taper, being generally largertoward the center (+) and gradually narrowing toward the perimeter orcircumference of the base. In some embodiments, the fulcrum can beslideably engaged with a channel 1308 or aperture of similar dimensions(FIG. 13A). By using a fulcrum design on the positive relief componentof each segment, the segments gain an angular deflection off the mainaxis in multiple directions while maintaining mechanical engagement withadjacent sections. This allows the segments to form a curce in two ormore planes normal to the main axis while mechanically engaged to oneanother. The fulcrum allows greater flexibility between segments anddoes not require the device to have any specific alignment in order togenerate a curved profile. The ability to remain in a loose, mechanicalengagement with adjacent segments provides added capability in thedevice. A guide wire or guide pin may thread through the central channeland provide an overall shape to the device and the various segments.

The fulcrum feature 1400 can now be seen in greater detail with fourdifferent views of the segment. In a plan view (FIG. 14A) the centralchannel 1418 and a group of peripheral channels 1416 a-n can be seen.Although four peripheral channels are shown, it should be understoodthat the number of peripheral channels may be as few as 1 or as many ascan be designed into the segment. Two side views of the segment 1400 areshown at 90 degree off sets. On one view (FIG. 14B), the side viewreveals the central channel creates a hole in the neck region. The neckregion raises the fulcrum above the top plate. Thus there may be a hole1426 in the neck 1422 1424 of the segment. In the rotated side view(FIG. 14C), the aperture 1404 for the fulcrum pin 1406 can be seen. Inthese embodiments, the fulcrum pin 1406 and fulcrum channel 1404 areshown in parallel. However the fulcrum pin 1406 and fulcrum channel 1404may be at any radial angle relative to each other. For example, thefulcrum pin and fulcrum channel may be offset anywhere from about 0degrees to about 180 degrees where the fulcrum pin and the channel aresymmetrical. Where the fulcrum pin is not symmetrical about the centralchannel, the fulcrum pin and fulcrum channel may be offset between 0degrees and 360 degrees. Additional detail can be seen in a perspectiveview (FIG. 14D) of the segment with a fulcrum style positive relieveelement. A circular perimeter 1402 can provide a smooth and atraumaticsurface for the segment 1400. The fulcrum 1406 is a generally taperedpin (by way of analogy only the fulcrum pin may be thought of as asingle piece wood rolling pin in shape) having a central channel 1418through it. The central channel 1418 exposes a hole 1426 on each side ofthe neck 1424. A fulcrum channel 1404 goes through the segment 1400 anddefines a fulcrum channel axis 1414. The fulcrum has two slopes 1408,1410 from the central channel 1418. The two slopes 1408, 1410 may be thesame, or they may differ in pitch, angle, shape or length.

An example of the fulcrum segments in a stacked arrangement is now shownin FIGS. 15A-B. The various segments 1502 a-n of the stack are shown ina perspective view in FIG. 15A. The individual segments have bendabilityin multiple planes, including a plane parallel to the direction of thefulcrum pin. A cross section (FIG. 15B) shows the individual angle ofdeflection 1312α of the main axis 1310 and the sum angle of deflection1312 a-n.

In an alternative embodiment, the fulcrum segments are shown with thefulcrum pins at 90 degree angles to the fulcrum channels (FIG. 16). Inthis embodiment the device 1600 has a distal end 1602 having a screwengagement device for engaging in the boney tissue. The main body 1604of the device 1600 is made up of fulcrum segments having fulcrum pinsrotated 90 degrees from the fulcrum channels. The fulcrum pins andchannels are able to engage mechanically and provide deflection anglesbetween each segment and a sum deflection angle that is the net of eachindividual deflection angle. A proximal end 1606 is shown whereindividual fibers 1608 n may be tensioned to hold the device 1600 in adesired shape. An alternative view of the device 1700 is provided inFIG. 17, having a distal end 1702, a body 1704 and proximal end 1706.The fibers 1708 n extend from the proximal end.

In some embodiments, the segments 1800 a-n of the device may havereplace the fulcrum pin and fulcrum channel individual round tabs 1802(FIG. 18A-B) and corresponding round apertures 1806 for receiving thetabs 1802. As previously described, the orientation of the tabs andapertures may be parallel or at any radial angle relative to each otheralong the circumference of the segment 1800. The segment tabs need notbe round, they may be ball shaped, or have acute angles. A shaped slotfeature 1810 may be made into one side of the segment to permit anothersegment to engage with the next segment. The sliding and stacking of thesegments may be done one at a time or in groups of two or more.

In some embodiments, the distal end 1900 may have a segment engagementportion 1906 to engage the fulcrum channel or fulcrum tabs for receivinga fulcrum pin/tab from a segment. The distal end may also have anegative relief feature for receiving a positive relief feature of asegment. In still another embodiment the distal end may have a positiverelief feature or fulcrum pin/tab for engaging a corresponding negativerelief feature, channel or aperture on an adjacent segment. The distalend has a bone engagement feature 1902 like a screw thread. The screwthread may have optional detents 1908, 1910 in the threading tofacilitate cutting into the bone for both clockwise and counterclockwise rotation. This helps in both placement and removal of thedevice should removal be required. A guide wire aperture 1904 may beprovided so the distal end may slide over the guide wire.

In some embodiments the distal end may be a screw head having agenerally tapered form with an oblong core (FIG. 20A). The distal endmay have an internal negative relief feature for receiving a hex bolt orother connection element from an adjacent segment. The connectionbetween the distal end and the distal most segment may be one where someangle of deflection is afforded to the overall device, or it may be aconnection with a solid fit and not additional angle of deflection ofthe main axis is gained between the last segment of the main body andthe distal end.

An end cap 2100 is provided for securing the proximal end of the mainbody (FIG. 21). In an embodiment, the end cap 2100 fits over theproximal most segment 2102 of the main body. The proximal most segment2102 may have a fulcrum tab 2104 for engaging other segments of the mainbody. The proximal most segment 2102 may also have a screw thread 2106for engaging the end cap 2100. One or more fiber channels 2112 areprovided for the fibers (not shown) to be gathered at the proximal endand drawn tight or simply fixed into position. The end cap 2100 slidesover the proximal most segment and can be screwed on to the proximalmost segment to engage the threads 2106. The end cap 2100 may betightened by hand by grasping or engaging the back section 2114 whichmay have a roughened surface to facilitate gripping. Alternatively theback section 2114 may be engaged using a torque driver. An optionalaperture or hole 2110 may be provided for the guidewire, fibers or otherloose ends that may trail from the device to be threaded through andremoved after the device is placed and capped. In some embodiments, thedevice is driven in to the bone via a torque driver transmitting torquedirectly to the proximal most segment 2102. The torque driver (notshown) would be adapted to accommodate the shape of the proximal end ofthe proximal most section. In some other embodiments, the device may bedriven in to the bone with a torque driver applying torque to the endcap 2100.

The end cap 2200 is now shown in a different perspective angle (FIG.22). The operator may hold the fibers in a group and place them into thethread channels 2210 and secure them in place. Generally one fiber perchannel, but the channels may be designed and cut to accommodate morethan one fiber. Between the channels are tabs 2206 which are optionallyintended to engage a torque transmission device to help drive the deviceinto the bone. Once the fibers are secured, the end cap 2200 may bescrewed into place over the proximal most segment 2202. Note theproximal most segment has a pair of fulcrum tabs 2204 for illustrationpurposes only. The fulcrum or connection/engagement mechanism to othersegments of the body may be any kind.

In some embodiments, the proximal end may be any form that can receive atorque transmission device and transmit torque to the body and thedistal end of the device. Various non limiting shapes adapted to receivetorque transmission devices are shown in FIGS. 23A-23F. In one nonlimiting embodiment, the relief feature for engaging a torquetransmission device is a positive relief feature 2300 having an endflange 2304 to prevent the proximal end from being pushed into the bonepast the hard cortical wall. In some embodiments there is a negativerelief feature 2308 for receiving the male end of a torque driver. Aflange 2312 or other feature is used again to help prevent the proximalend from being driven past the hard bone wall. A hole or aperture 2306,2310 is made in the proximal end for the passage of a guidewire.

FIG. 24A shows an alternative embodiment of a body 2400 having pairs2402, 2408 of slots disposed circumferentially around the body tube, andoffset by about 90° from each other. In an unbent state, the slots mayhave a width 2400 w. The body 2400 is bent downwardly away from thelinear axis 2406 and defines an offset axis 2412 wherein a width 2400 w_(b) of at least one slot 2410 on the lower side may be narrowed and awidth 2400 w _(a) of at least one slot 2404 on the upper side may beincreased to allow the body to bend downwardly.

In some embodiments, as represented in FIGS. 24B, 24C and 24D, the body2400 may be locked in its bent configuration by providing radiallyinwardly disposed teeth 2422 on the interior surface of the body 2400,which teeth extend through the main body. One or more externally toothedfibers 2414 may be inserted within the central cannula 2424. The toothedfibers 2414 may include teeth 2420 that match the pitch of the teeth2422 (or threads) on the inside of the outer member so that the teeth onthe fibers may engage with the teeth on the interior surface. In theflexible state, the internal fibers 2414 in the main body havesufficient diametric clearance to translate axially through the mainbody. In these embodiments, the tooth pitch is generally fine scale so aseries of engaged teeth form between the inside of the body and thetoothed fibers. Where the device has a bend in it, and the toothfrequency changes over any particular length, the fine scale of theteeth allows gaps and teeth to engage on a less than 1:1 or more than1:1 ration and still provide gripping or engagement friction so theparts remain relatively stationary to each other when in a fixed shape.

In an embodiment as shown, the fibers 2414 may have a rectangularcross-section with teeth 2420 on one surface thereof. In alternativeembodiments, the fibers 2414 may have teeth on each surface, or thefibers may have a circular cross-section and may have circumferentialteeth or threads. To provide and maintain engagement of the teeth 2420with the teeth 2422, an internal core component, or filler 2418, shownin cross-section in FIG. 24D, may be inserted longitudinally into thecannula 2424 to hold the fibers 2414 adjacent the interior walls.

The entire main body may be converted to a rigid state upon theinsertion of the filler 2418, which pushes the teeth 2420 of theinternal fibers 2414 against the teeth of the main body, meshing thethreads/teeth of the internal members, creating a load path from onerigid section of the main body to the internal tension members,(bypassing the flexible section of the main body) to the next rigidsection of the main body. The fibers 2414 may terminate within the mainbody, or in members attached to either end of the main body, forexample, the proximal or distal bone interfaces. The internal core, orfiller 2418, may be formed of materials that are flexible (bendable) forinsertion along a curved path, but minimally compressible so that thefibers 2414 remain pressed into engagement with the interior surface.Some examples of materials from which the filler 2418 may be constructedinclude, but are not limited to SS 316LVM, Titanium Grade 23 6Al-4V ELI,PPEK or any 236LVM Stainless steel, polyether ether ketone (PEEK), orother materials as described herein.

In an embodiment, wherein three fibers 2414 (shown in cross-section inFIG. 24D) may be internally disposed within the body 2400, the fibersmay be disposed at about 120° with respect to one another to therebyprohibit movement (bending) in all directions orthogonal to thelongitudinal axis. In additional embodiments, additional fibers may bedisposed within the cannula to provide additional shape-lockingcapability. For example, four fibers may be circumferentially spaced atabout 90° from one another, or six fibers may be circumferentiallyspaced at about 60° from one another, or eight fibers may becircumferentially spaced at about 45° from one another. The number offibers may be varied depending on the diameter of the body, and/or theintended use, such as severity and location of the fracture and stressthat may be applied to the fractured bone.

In some embodiments, the body 2504 of the device 2500 may be made of asingle component (FIG. 25). In these embodiments, the body may be madeof a flexible polymer material, a flexible metal or alloy tube or acombination of both. In some embodiments, the flexible tube may drawfrom existing manufacturing techniques for catheters, endoscopes andother minimally invasive medical device designs. In some embodiments thedistal end 2502 retains a screw thread for engaging boney tissue and atorque transmission proximal end 2506 to allow torque to be transferredfrom the proximal end, along the body and too the distal end. The bodymay be a multilayer polymer device with metal wire or ribbon braid. Sucha design may have added rigidity to enhance pushability andtorquability. In some embodiments a catheter or endoscope constructiontechnique can allow for an enlarged central lumen, through which a multisegmented body or other core like device may be inserted. In someembodiments the single tube body device may have a flange on theproximal end to act as a stop and prevent the device from being insertedtoo far into the bone (FIG. 26). The proximal end may be equipped with aflange 2606 so the device 2600 does not become completely inserted intothe intramedullary space of the bone. Such an insertion may makeretrieval and removal of the device difficult. The device 2600 has abody 2604 which may be a unibody design or a multi-segmented body. Adistal end 2602 is also provided.

In some embodiments, the device 2700 may use a tube or other design forthe main body 2704 having a series of slots, apertures or other stressrelief elements built into the body structure. In an embodiment, aseries of slots 2708 _(a-n) are constructed as part of the body 2704.When torque is applied to the proximal end 2706, the body 2704 cantransfer the torque to the distal end 2702. The individual slots orapertures 2708 _(a-n) provide stress relief or enhance torque andflexibility, allowing the body to rotate on its axis and deliver torqueto the distal end with compromising the structural integrity of thedevice. The body 2704 may be solid or hollow, or multi lumen withvarious component layers. In some embodiments the body 2704 may have alarge central lumen to accommodate a multi-segment core or othermaterial to provide enhanced structural features, allowing pushability,torquability and radial stiffness.

In an additional unibody-type configuration, a unibody support device2700 may be constructed of a non-flexible, torsionally stiff material,such as, for example, titanium as presented above (FIG. 27). In anembodiment, the body 2704 may be include a plurality of spaced apartslots 2708 _(a-n) or other apertures that extend circumferentially abouta portion of the exterior surface. The apertures may be arrangedfollowing a helical pattern around the tube shaped body. In anembodiment the slots may be configured as pairs, with each slot of apair being disposed at about 180° from the other slot of the pair,thereby allowing for widening of the slot on one side, while theopposite slot is narrowed for bending in the direction of the narrowedslot. As shown, the slots 2708 _(a-n) may also be circumferentiallyoffset from one another. In an embodiment, the slots may becircumferentially offset from each other by about 60° to 90°, therebyallowing for bending of the body 2704 to occur in a multiplicity ofdirections, as may be required for cannulae of complex curvature, orcurvature in more than one plane.

The distal bone interface 2702 and the proximal bone interface 2706 maybe integral with the body 2704, or may be separate attached components,of any of the embodiments as discussed herein. The proximal section 2706depicts a radial flange for axial bone fixation, and depicts a negativerelief hex configuration for torque transmission, and the distal boneinterface 2702 is depicted as a threaded screw head with bone cuttingthreads. The bone cutting threads may be regular pitch or variablepitch, continuous or interrupted/interval; type. In some embodiments,threads may be replaced or augmented with spikes, pins, nails or anyother mechanism in addition or alternative to screw threads. A profileview is now shown in FIG. 28, having a profile view of the device 2800with a proximal section 2806, body section 2804 and a distal end 2802.

In still other embodiments, the device 2900 may have a body 2904 madefrom a single tube, but cut using any acceptable cutting technique(laser, EDM, mechanical blade) to produce a long continuous scar orslice through the tubular body (FIGS. 29A-29B). The cut 2910 may becompletely through the tube body so the cut punctures the shell of thetube, or the cut may be an etching or partial cut that produces a gougeor trench in the tube body without penetrating the tube body. In someembodiments the cut 2910 may be alternating cuts through the tube bodyand gouges that do not penetrated to the interior of the tube body. Onemay imagine this sort of scoring as a dashed line of through cuts andpartial cuts. The device 2900 has a distal section 2906 and a proximalsection 2902. The device 2900 in a linear state defines an axis 2908,and the type of cut line 2910 and its depth in the body will define howfar the device 2900 can be deflected or bent off its main axis. The cutline 2910 may be made to start at one end of the tubular body andcontinue to the other end. The number of turns the cut line 2910 makesin a given unit of linear length defines the frequency 2912 of the cutline. Generally the higher the frequency, the greater deflection off themain axis the device 2900 can make. Alternatively by increasing thewidth of the cut, a similar result (greater angle of deflection) can beachieved. The cut line 2910 may have variable cut width as well asdepth.

The proximal end may come in a variety of shapes, sizes and features. Insome embodiments of the proximal end, there may be a flange 3008, 3010of varying shapes and sizes. The flange is generally intended to preventthe proximal section of the device 3000 from being inserted past thecortical wall of the bone being treated. Access to the proximal end isgenerally important in case the patient has a post operativecomplication which requires removal of the device. The medicalprofessional then needs ready access to the device without beingrequired to dig into the bone to retrieve the device. A flange orsimilar feature may be used to prevent the device from being insertedtoo far into the intramedullary space. In some embodiment the proximalend 3004 may be tapered such that part of the proximal end can enterpast the cortical wall and part of the proximal end cannot enter pastthe cortical wall. In some embodiments the proximal end may be threadedso there is a feature or element that will engage the cortical wall. Thedistal head 3002 similarly may have a bone engagement thread.

In some embodiments, the distal end may use articulable disks 3102 andclamps 3112 to engage the bone. In some embodiments, the disks 3102 areprovided in a first position which is narrower in profile to allowinsertion into the intramedullary bone space (FIG. 31). The clamps 3112are in a low radius configuration to allow the device to be advanced.When the device is in the proper location, the disks 3104 compresses onthe clamps 3114 forcing the clamps radially outward, and thus engage theboney tissue. This action may occur when the fibers are drawn tight, orwhen the device is withdrawn slightly to cause the disks or clamps toengage the boney tissue, or the disks or clamps may be actuated usingsome sort of user control mechanism. Various non-limiting designs forthe disks and clamps are provided 3106, 3108, 3110. The clamps may besimilar to washers or lock washers in shape.

In some embodiments, placement of the device may be facilitated by usinga curved intramedullary fixation (CIF) steerable guidewire, or simplyguidewire 3300 (FIG. 33). The guidewire 3300 maybe one generally used inorthopedic procedures, and may be about 0.3 mm to 6.0 mm in diameter.The diameter of the guidewire can be selected by the medicalprofessional and appropriate for the bone the guidewire will be used on.The guidewire 3300 has a bend 3302 near the distal end 3304, and thedistal end may be tapered to a point. In operation, a medicalprofessional may pass the guidewire 3300 down the bone and tap on theproximal end of the guidewire to incrementally advance the guidewire inthe intramedullary space of the bone. The guidewire is rotated so thebend 3302 portion of the guidewire is angled toward the cortical wall.Thus when the user taps on the proximal end of the guidewire, the distalend is deflected away from the cortical wall when the bend portionimpacts the wall. In this manner, the guidewire may be continuouslyrotated by the medical professional under visualization so the guidewirecreates a curved path through the intramedullary space.

The guidewire, the device and other components as described here in, maybe made from a wide range of materials. In the various embodimentsdescribed herein, the device and the guidewire may be composed from apolymer, a metal, an alloy, or a combination thereof, which may bebiocompatible. For example, the guidewire or device can be formed fromTitanium Grade 23 6Al-4V ELI material or 316 LVM Stainless steeltitanium or a titanium alloy. Other suitable metals may includestainless steel, cobalt-chromium alloys, and tantalum. In someembodiments, metal alloys having shape memory capability, such as nickeltitanium or spring stainless steel alloys, may also be used. In someembodiments, the guidewire and device can be formed from a suitablepolymer including non-degradable polymers, such as polyetheretherketone(PEEK) and polyethylene (PE), as well as modified versions of thesematerials (for example, PEEK+calcium phosphates and PE+vitamin E, metalcoatings, or surface texturing). Additional non limiting polymers mayinclude; polyether-block co-polyamide polymers, copolyester elastomers,thermoset polymers, polyolefins (e.g., polypropylene or polyethylene,including high density polyethylene (HDPEs), low-density polyethylene(LDPEs), and ultrahigh molecular weight polyethylene (UHMWPE)),polytetrafluoroethylene, ethylene vinyl acetate, polyamides, polyimides,polyurethanes, polyvinyl chloride (PVC), fluoropolymers (e.g.,fluorinated ethylene propylene, perfluoroalkoxy (PEA) polymer,polyvinylidenefluoride, etc.), polyetheretherketones (PEEKs),PEEK-carbon fiber composites, Polyetherketoneketones (PEKKs),poly(methylmethacrylate) (PMMA), polysulfone (PSU), epoxy resins andsilicones. Additionally starch based polymers may be used.

Additional materials may include carbon and polyaramid structures, glassor fiberglass derivatives, ceramic materials, and artificialbiocompatible protein derivatives (recombinant derived collagen). Inother embodiments, the fracture stabilization device may be made of ametal and/or alloy segments with a polymer shell, or a sandwich styleand coaxial extrusion composition of any number of layers of any of thematerials listed herein. Various layers may be bonded to each other toprovide for single layer composition of metal(s), alloys, and/orpolymers. In another embodiment, a polymer core may be used with a metaland/or metal alloy shell, such as a wire or ribbon braid.

Additionally, at least a portion of the device may include a boneintegration surface to promote bone ingrowth, on-growth, and/orthrough-growth between the segments, if desired. The bone integrationsurfaces can comprise a three-dimensional space to allow boneintegration into and/or onto portions of the fracture stabilizationdevice. The three dimensional space can be provided by athree-dimensional substrate, for example beads, and/or by the provisionof holes through the bone integration portions. Other methods forachieving bone integration can include the provision of an appropriatesurface topography, for example a roughened or textured area and/or bythe provision of osteoconductive coatings, such as calcium phosphates.The bone integration surface may enable the fracture stabilizationdevice to provide a metal and/or polymeric scaffold for tissueintegration to be achieved through the fracture stabilization device. Invarious embodiments, various materials may be used to facilitate,stimulate or activate bone growth. A non-limiting list of materials mayinclude hydroxyapatite (HA) coatings, synthetic bioabsorbable polymerssuch as poly (α-hydroxy esters), poly (L-lactic acid) (PLLA),poly(glycolic acid) (PGA) or their copolymers,poly(DL-lactic-co-glycolic acid) (PLGA), and poly(ε-caprolactone) (PLC),poly(L-lactide) (LPLA), (DLPLA), poly(e-caprolactone) (PCL),poly(dioxanone) (PDO), poly(glycolide-co-trimethylene carbonate)(PGA-TMC), poly(lactide-co-glycolide), polyorthoesters, poly(anhydrides), polyhydroxybutyrate, poly(l-lactide-co-glycolide)(PGA-LPLA), cyanoacrylates, poly(dl-lactide-co-glycolide) (PGA-DLPLA),poly(ethylene carbonate), poly(iminocarbonates),poly(l-lactide-co-dl-lactide) (LPLA-DLPLA), andpoly(glycolide-co-trimethylene carbonate-co-dioxanone) (PDO-PGA-TMC).

EXAMPLES OF THE USE OF THE SUPPORT DEVICE ARE NOW PROVIDED Example 1Device Insertion

In an embodiment, the support device has a proximal end, a distal end,and an elongate main body. The proximal end includes a flexibilityfixation element that serves to lock the support device into a rigid orinflexible shape when desired. The support device may include anoptional sheath to enhance the atraumatic profile of the support devicewhen used. After the patient is properly prepared and oriented so thesurgeon, doctor or other medical professional can access the desiredlocation of the body, the trocar 3204 can be assembled with a protectivesleeve 3202 to access the pelvis P. The assembled protective sleeve 3202and trocar 3204 are used to pass through soft tissue to the desiredentry point E on the bone. When the trocar and protective sleeveassembly are properly placed, a user may strike the trocar with ahammer, cannulated hammer or other instrument 3206 to create a startingpoint in the bone for the procedure (FIG. 32A-L). In this example, thepelvis P has suffered a break B in two locations. The break in theSacrum is not treated in this example.

A start drill 3208 or similar device may be inserted through theprotective sleeve 3202 and advanced through the cortical bone. Thiscreates a portal for all instruments and devices to pass through as theyenter the bone P (FIG. 32B).

The start drill may be removed and a steerable guide wire, guide pin orCIF steerable guide wire (collectively simply referred to herein as a“guidewire” 3210) may be inserted through the protective sleeve 3202 andthe trocar 3204. A physician or other medical professional may usefluoroscopy or other visualization technology to view the guidewire inthe bone. The CIF guidewire is advanced through the medullary canal. ByRotating the CIF steerable Guidewire and applying force on the proximalend, a desired placement can be achieved. The guidewire is advanced tothe proximity of the cortical wall of the Pubis symphysis and across thebreak B (FIG. 32C).

Once the medical professional is satisfied with the placement of the CIFsteerable guidewire 3210, a cannulated flexible reamer 3212 may bepassed over the guidewire and used to ream the cancellous bone. Thesurgeon should exercise care not to ream through the bone past thedistal end of the guidewire 3210 d (FIG. 32D).

When the medical professional is satisfied the reaming is completed, thereamer tool and the guidewire are both removed. A directional exchangetool 3214 is introduced through the protective sleeve 3202 and into therecently reamed channel in the medullary canal. It may be useful toplace the cone shaped geometry of the directional exchange tool adjacentto, and as normal as possible to, the cortical wall (FIG. 32E). A trocartipped guidewire 3216 is then passed through the directional exchangetube 3214. The trocar tipped guidewire 3216 is placed down to thecortical wall CW (FIG. 32F). The user than applies force, eithermanually or via some mechanical advantage device) on the proximal end ofthe trocar tipped guidewire 3216 until both cortices of the PubisSymphysis have been perforated (FIG. 32G).

Once both cortices have been pierced, the trocar tipped guidewire isremoved and a second steerable guidewire 3218 is introduced. If theperforations in the cortical wall CW are not large enough, it may benecessary to ream the holes out until they are sufficiently large toaccommodate the passing of the guidewire. The medical professional thencrosses the guidewire to the Pubis Sympysis and medullary canal acrossthe pubic arch (FIG. 32H). A reamer 3220 is used to finish creating thepath between the two side of the pubic arch (FIG. 32I).

When the reaming is completed, the medical professional can introduce anexchange tube 3222 over the guidewire 3218. The exchange tube 3222 isthen advanced over the guidewire to the distal end of the guidewire(FIG. 32J). Once the exchange tube 3222 is properly placed, theguidewire may be removed and a trocar tipped guidewire 3224 isintroduced and advanced to approximately the same distal location. Theexchange tube 322 can then be removed (FIG. 32K). The device 3200 cannow be advanced over the guidewire 3224. The device 3200 may need to beadvanced using any appropriate torque driver 3226, such as a hexalobedriver, screw driver or drill tool to name a few. Once the device isproperly placed across the break B and the pubic arch, the shape devicecan be secured in place by drawing tight any fibers in the device tosecure the position of the segments, or simply deploying a proximal endwith a bone engagement element to secure the device 3200 in the bone(FIG. 32L).

The device has a distal end which is rounded and oblong with a screwthread designed to help cut into the bone structure when the supportdevice is deployed. The shape of the distal end may be adapted for avariety of different types of bones and bone densities. The shape anddesign of the distal end should be adaptive to not overly stress weakerbones (such as in patients who are elderly and may suffer fromosteoporosis). Similarly the shape, thread pitch and cutting edge shouldbe adapted for stronger bones if the support device is to be placed intothe bone of someone younger and healthy (such as an athlete).

Example 2 Surgical Procedure for Fixation of Pelvic Fracture

The device may be used to stabilize fractures in the ilosacral areaposteriorly, the anterior column of the acetabulum, the superior pubicramus, the posterior column of the acetabulum, the pubic symphysis aswell as other areas. The device may be adapted for use in ribs, thesternum, collar bones, shoulder blades or even long bones of the body.

The procedure used to treat bones can be generically thought of tofollow and be similar to, the procedure to insert cannulated cancellousscrews in some areas (but not all). The curved intramedullary device isnot a reduction device and as with the use of cannulated screws, thesurgeon generally should reduce the fracture and temporarily stabilizeit before employing the current device. The device can secure the pubicrami and the symphysis at the same time. In an example procedure, thepatient would be placed supine on a radiolucent operating table andprepped and draped exposing the entry points chosen for the particularprocedure. For example, for a vertical shear type of pelvic fracturewith disruption through the sacrum at the back and the pubic ramus atthe front, the pubic area and the posterolateral buttock area would beexposed.

After the fracture is reduced and temporarily held by whatever methodthe surgeon needs, a small incision is made of the pubic tubercle on theaffected side and the lateral side of the tubercle exposed. A small holeof about 2-5 mm (millimeters) is drilled through the cortex in themiddle of the lateral side of the tubercle and a special curvedguidewire is introsduced into the medullary space of the superior pubicramus. Using the image intensifier as a guide and using appropriateimaging views, the guide wire is advanced, not by drilling, but byhammering. Alternative embodiments advance the wire by drilling. Anotheralternative embodiment has a guidewire which has a drill featureincorporated into its distal end to facilitate drilling through the bone(which may be either cancellous or cortical).

The hammering of the guidewire can be done with a standard hammer or ahammer drill. The wire is carefully advanced inside the pubic ramus andthe anterior column, past the acetabulum staying inside the bone. Thelength of the wire inside the bone is measure and an appropriate lengthof curved intramedullary device is chosen. A flexible reamer of 8.5 mmis placed over the guidewire and drilled in, again under fluoro control,making a tunnel in the bone. Using an exchange tube, the sharp benttipped guidewire is exchanged for a blunt tipped guidewire. The reamerand guidewire are removed and the chosen curved intramedullary device isscrewed into the tunnel over the guidewire using a torque driver.

Because the device is flexible, it is easier to insert it through acannula. Once in place, one embodiment has a star shaped screwdriverused to tighten then tensioning wire and compress the elements of thedevice together to make them rigid. A capping nut is then applied to theproximal end to add mild compression and to prevent the bone fromslipping off the end of the device. Once in place, the device is maderigid.

Example 3

Attention is then directed posteriorly, the surgeon chooses a startingpoint on the lateral surface of the ilium above the sciatic notch. Thestarting point is not quite as critical as it is in using a cannulatedscrew since the guidewire follows a curved path of the surgeon'schoosing and the path can be modified in situ more easily than can thepath of a straight wire. Because of the bulk of the soft tissue of thebuttock, this procedure would be done through a series of stackedcannulae.

Example 4

The procedure is then the same as described for the anterior fixation. Ahole is drilled at the desired access point, and a curved guidewire ishammered across the SI joint and across the body of the sacrum throughS1 and if needed across the far SI joint in the ilium, measuring,reaming, guidewire exchange, insertion of the device and tightening ofthe tension fibers of the device. It may be needed to tighten thewires/fibers of the anterior and anterior devices at the same time, orin synchronized fashion, to be sure that tightening one does not movethe fracture in the other site. Once the device is in place, the woundsare closed, final X-rays are taken and dressings are applied.

Example 5

Alternative embodiments include a flexible/rigid device (as describedherein) to fixate an anterior pelvic fracture along with conventionalscrews or plates to fixate a posterior fracture.

Example 6

Another alternative embodiment includes a flexible/rigid device (asdescribed herein) to fixate an posterior pelvic fracture along withconventional screws or plates to fixate an anterior fracture.

Example 7 Device Removal

In an embodiment, the support device may need to be removed afterimplantation. This may be referred to as explantation or simply removal.In this embodiment the operator must once again access the entry site onthe bone that was previously treated with the flexible support device.The proximal bone interface may be rotated off, or removed in theappropriate manner to expose the shape locking element. The shapelocking element is engaged with a tool that can disengage the shapelocking mechanism in a manner that will allow the support device toreturn to a flexible state. The support device is then removed from thebone. If the support device was “screwed” in, it can be rotated in theopposite direction and unscrewed from the bone. The tool may interfacewith either the proximal end, the shape locking element, or otherreadily accessible feature on or near the proximal end. It may benecessary to remove some bone ingrowth from the support device in orderto gain sufficient access to the implanted support device when removalis desired.

Rotation of the proximal end of the device transmits torque through thesupport device up to the distal bone interface. The torsional responseof the main body sections may result in a section by sectiondisengagement with any bone ingrowth. The most proximal section islikely to break free first, with the segments breaking free in sequencedown to the most distal end. It is also possible that entire sectionswill break free at once, or the device will break free all together.When the support body has broken free of the bone ingrowth, the supportbody may be removed.

EMBODIMENTS

1. A medical apparatus for bone fixation, the apparatus comprising:

-   -   a flexible body defining a main axis, the flexible body having a        proximal end and a distal end, the flexible body comprising:        -   a plurality of individual segments having a mechanical            engagement structure for non-rigidly interlocking the            individual segments together;        -   a plurality of apertures in each individual segment, the            apertures arranged to generally form a plurality of lumens            in the flexible body when the segments are in non-rigid            mechanical engagement;        -   wherein the individual segments may move relative to each            other in a first and a second orthogonal plane relative to            the main axis;    -   a torque transmission member positioned substantially on the        proximal end;    -   a bone engagement feature positioned substantially on the distal        end; and    -   a plurality of fibers extending through the lumens such that the        fibers provide a fixed shape to the flexible body when the        fibers are fixed into position.

2. The apparatus of embodiment 1, wherein the individual segmentspossess a first and a second end, the first end having a mechanicalengagement structure (male end) and the second end having a shapedreceptacle for receiving a similarly shaped mechanical engagementstructure (female end) such that the interconnection between themechanical engagement structure and the shaped receptacle forms amechanical interlock allowing movement between the mechanically engagedindividual segments.

3. The apparatus of embodiment 2, wherein the mechanical engagementstructure operates as a fulcrum.

4. The apparatus of embodiment 2, further comprising a second mechanicalengagement structure.

5. The apparatus of embodiment 2, further comprising a second shapedreceptacle.

6. The apparatus of embodiment 1, wherein the flexible body issub-divided into sections.

7. The apparatus of embodiment A4, wherein each section comprises one ormore segments.

8. The apparatus of embodiment 1, wherein said fibers are of two or moreindividual lengths when drawn taut.

9. The apparatus of embodiment 1, wherein the individual segments arenot of uniform size, shape, mass or length.

10. The apparatus of embodiment 1, wherein the individual mechanicalengagement structures are not uniform from segment to segment.

11. The apparatus of embodiment 1, wherein the individual shapedreceptacles are not uniform from segment to segment.

12. The apparatus of embodiment 1, further comprising a sheath extendingover the flexible body.

13. The apparatus of embodiment 1, wherein the fibers are mechanicallyfixed into position.

14. The apparatus of embodiment 1, wherein the fibers are chemicallyfixed into position.

15. A medical apparatus for bone fixation, the apparatus comprising:

-   -   An elongate tubular body defining a first axis, the body having        a proximal end, a distal end and a lumen there through, the        tubular body having a plurality of apertures;    -   a torque transmission member located substantially at the        proximal end;    -   a bone engagement feature located substantially at the distal        end;        -   wherein the plurality of apertures provide stress relief            along the elongate body when the tubular body is under            torque.

16. A medical apparatus of embodiment 15, further comprising astiffening member within the lumen.

17. A medical apparatus of embodiment 16, wherein the stiffening memberis a spring.

18. A medical apparatus as in embodiment 16, wherein the stiffeningmember is a single rigid member.

19. A medical apparatus as in embodiment 15, where a chemical compoundcauses radial expansion of the tubular body.

20. A medical apparatus for fixation of fractured bone, the apparatuscomprising:

-   -   an elongated body defining a longitudinal axis, and having a        proximal end and a distal end spaced longitudinally from the        proximal end by a first distance, the body comprising:        -   a flexible body portion extending along at least a portion            of the first distance, the flexible body portion comprising            a plurality of interconnected segments, wherein each segment            of the interconnected segments defines an axis portion of            the longitudinal axis, and each segment is movable with            respect to at least one adjacent segment to angularly offset            the axis portion of each segment with the axis portion of            the at least one adjacent segment;    -   a transmission member positioned adjacent the proximal end for        axially inserting the elongated body into the bone;    -   a bone engagement device positioned adjacent the distal end for        axially retaining the elongated body within the bone;    -   a plurality of cables disposed longitudinally within the        elongated body through at least the flexible body portion in        circumferentially spaced relation to one another; and    -   a cable tensioning system for tensioning individual ones of the        plurality of cables to retain the interconnected segments in a        fixed relationship with each of the plurality of cables and with        one another.

21. The medical apparatus of embodiment 20, wherein:

-   -   the plurality of interconnected segments comprises a plurality        of individual interconnected segments; and    -   each individual segment having a first end and a second end        spaced axially from the first end; and    -   at least one of the first end and the second end of each segment        comprises a first engagement portion for pivotally engaging with        the other of the first end and the second end of an adjacent        segment to angularly offset the axis portion of the segment with        the axis portion of the at least one adjacent segment.

22. The medical apparatus of embodiment 21, wherein:

-   -   the first engagement portion comprises a protrusion extending        axially from the first end; and    -   the other of the first end and the second end comprises a        recessed portion for receiving the protrusion therein.

23. A method of fixing a reduced bone fracture in a curved bone, themethod comprising:

-   -   creating an entry into a curved bone;    -   advancing a guidewire through an intramedullary space to a        position distal to a reduced bone fracture;    -   reaming a channel in the intramedullary space along the length        of the guidewire;    -   advancing a curved intramedullary fixation device through the        channel; and    -   locking the curved intramedullary fixation device in place.

What is claimed is:
 1. A medical apparatus for bone fixation, theapparatus comprising: a flexible body defining a main axis, the flexiblebody having a proximal end and a distal end, the flexible bodycomprising: a plurality of individual segments having a mechanicalengagement structure for interlocking the individual segments together;a plurality of apertures in each of the individual segments, theapertures arranged to generally form a plurality of lumens in theflexible body; wherein the individual segments are configured to moverelative to each other in a first plane and a second plane, and whereinthe first plane and the second plane are orthogonal relative to the mainaxis; a torque transmission engagement feature positioned substantiallyon the proximal end; a bone engagement feature positioned substantiallyon the distal end; and a plurality of fibers that extend through thelumens such that the flexible body is locked when the fibers are fixedinto position relative to each other.
 2. The apparatus of claim 1,wherein when the flexible body is locked, the individual segments areheld together in a fixed relationship.
 3. The apparatus of claim 1,wherein the fibers are mechanically fixed at the distal end.
 4. Theapparatus of claim 1, wherein a placement of the fibers within theapertures of the individual segments support shear loading between theindividual segments.
 5. The apparatus of claim 1, wherein each of theindividual segments comprises a first end and a second end, the firstend having a male type mechanical engagement structure and the secondend having a female type receptacle configured to receive a male typeshaped mechanical engagement structure.
 6. The apparatus of claim 5,wherein the male type mechanical engagement structure operates as afulcrum.
 7. The apparatus of claim 5, wherein the male type mechanicalengagement structure and the female type receptacle are configured totransfer torque between the individual segments.
 8. The apparatus ofclaim 5, wherein the male type mechanical engagement structure and thefemale type receptacle of at least two of the individual segments are ofdifferent sizes.
 9. The apparatus of claim 5, wherein the male typemechanical engagement structure and the female type receptacle areconfigured to prevent the individual segments from separating when atensile force is applied between the proximal and distal ends.
 10. Theapparatus of claim 1, wherein at least two of the fibers are ofdifferent lengths.
 11. The apparatus of claim 1, wherein at least two ofthe individual segments are of different sizes shapes, masses, orlengths.
 12. The apparatus of claim 1, wherein the fibers are configuredto move relative to each other at the proximal end when the device is ina flexible state, and further wherein the fibers are configured to bemechanically fixed into position relative to each other at the proximalend when the device is in a rigid state.
 13. The apparatus of claim 12wherein the fibers are configured to be mechanically fixed into positionat the proximal end of the device with an end cap when the device is ina rigid state.
 14. A medical apparatus for fixation of fractured bone,the apparatus comprising: an elongate body having a proximal end and adistal end, the elongate body comprising: a flexible body portioncomprising a plurality of interconnected segments; a torque transmissionengagement feature positioned at the proximal end configured to screwthe apparatus into the bone; a bone engagement feature positioned at thedistal end configured to retain the elongate body within the bone; aplurality of fibers disposed longitudinally within the elongate bodycircumferentially spaced in relation to one another.
 15. The medicalapparatus of claim 14, wherein at least one of the interconnectedsegments comprises a first engagement portion for pivotally engagingwith at least one end of an adjacent interconnected segment.
 16. Themedical apparatus of claim 14, wherein: a first engagement portioncomprises a protrusion extending axially from a first end of at leastone of the interconnected segments; and a second end of at least one ofthe interconnected segments comprises a recessed portion configured toreceive the protrusion therein.
 17. The medical apparatus of claim 16,wherein the protrusion and the recessed portion of each one of theinterconnected segments are radially spaced approximately ninety degreesfrom each other.
 18. The medical apparatus of claim 16, wherein thefirst engagement portion comprises two individual tabs and the recessedportion comprises two apertures.
 19. The medical apparatus of claim 18,wherein the interconnected segments comprise an outer cylindricalsurface, and further wherein at least one side of the two individualtabs coincides with the outer cylindrical surface.
 20. The medicalapparatus of claim 16, wherein: the bone engagement feature comprises anend recessed portion configured to receive one the first engagementportion of one of the interconnected segments; and the torquetransmission engagement feature comprises an end protrusion configuredto be received by the recessed portion of one of the interconnectedsegments.
 21. A method of fixing a bone fracture in a curved bone, themethod comprising: creating an entry into the curved bone; advancing aguidewire through a curved intramedullary space to a position distal tothe bone fracture; advancing a flexible intramedullary fixation deviceover the guidewire; and shape locking the flexible intramedullaryfixation device to convert the flexible intramedullary fixation deviceinto a rigid configuration to fixate the bone fracture.
 22. The methodof claim 21, wherein the curved bone is a bone of a pelvis.